Treating petroleum derivatives and products thereof



l Nv. 21,1944., .A w FRANCIS 2363;-171

TREATING PETROLEUM DERIVATIVES AND PRODUCT THEREOF Filed Jan. 21, 1942 AT'roRNEY Patented Nov. 21,1944

TREATING PETROLEUM DERIVATIVES AND PRODUCTS THEREOF Alfred W. Francis, Woodbury, N. J., assigner to Socony-Vacuum Oil Company, Incorporated, New York, N. Y., a corporation of New' York Application January 21, 1942, Serial No. 427,546 sclaims. (cl.2sos73.5)

This invention relates to a process for treating.

petroleum derivatives and is more specifically directed to a process for removing a fraction from `gasolines made up primarily of isomeric octanes and treating the removed fraction to convert the constituents thereof to more valuable hydrocarbons which may then be returned tothe gasoline or utilized for other purposes for which it is well suited.

I Aviation gasolines of octane values, unleaded, in the neighborhood of 90 are readily prepared on a commercial scale by processes now in rather wide use. For example, a very high grade motor A fuel is 'derived by alkylation of iso-butane with ment of these products,known as alky1ate, by

treatment in a manner disclosed below.

I have found that the octane number of these alkylates may be greatly improved by removing therefrom the fraction boiling between about 104 C. and 111C., subjecting the removed fraction to an aromatization treatment and returning it to the alkylate. As a general rule, removal of vthe said fraction, which normally constitutes about 15% of the alkylate, raises the octane number from about 94 for the alkylate to about l9 7 for the residue; while return of thetreated fractions gives a composition having an octane number of at least 100.

Preferably the alkylate is originally prepared' from line 3 and the mixture agitated and pro-j` pelled through 'return pipe 4 bymeans of pump 5. Fresh" feed stock, including iso-butane4 and butylenes, from a suitable source supplied through pipe 6 and recycled iso-butane from recycle line 1, are added to the stream in pipe 4 and the whole is then supplied to the body of fluids in reactor I, preferably -With agitation.

A second stream is withdrawn from the mass-in reactor I, and passed by means of pipe 8 to a 'y settler 9 wherein the uid catalyst is separated by alkylation of iso-butane with butylenes in the 'presence of a fluid acid catalyst such as sulphuric acid, hydrofluoric acid and the like. A specific embodiment of the invention is therefore discussed herein asl including such an alkylation step and the process may advantageously be conducted in a. plant constructed in accordance with the annexed drawing which is a diagrammatic in suitable proportions, as is well known in the art. From -the reactor I, a stream of the reaction mixture is continuously withdrawn through line from the hydrocarbons andthe acid layer withdrawn through line I0, a part of the acid being preferably recycled to the process while the remainder is withdrawn from the system as spent catalyst. The hydrocarbon layer from the set-l tler 9 is passed through line II to a fractionator wherein light gases such as propane are separated out for use as fuel and other purposes to which the gas is suited. Thence the liquid bottoms 4are transferred to fractionator I 3 from which iso-butane contained therein is taken overhead for recycling to the alkylation reactor l, as noted above.

The remaining hydrocarbons are then transferred to a fractionating column I4, wherein an intermediate fraction boiling between 195i and 130 C. is taken as alkylation product through line I5, while light and heavy ends are rejected through lines I8 and II, respectively. Thus far,

the process is more o r less conventional and may be operated in accordancewith any of the suitable methods,.of which many types and variations are known. It is to be understood. of course, that apparatus for the present purpose, described both above and below, includes such additional equipment as reboilers, pumps, valves and the like where desirable between settler 9 and fractionator I2. included is a caustic washing stage.

'I'he product drawn ofl through line I5 is usually a fractionA consisting predominantly of iso- 2, a portion of fresh catalyst is added thereto merio octanes varying in physical properties and in octane number. Among these are some portions which havea relatively low octane number and which tend to seriously reduce the octane number of the alkylate, either 'as a motor fuel alone oras a blending agent for preparation of high anti-knock gasolines from inferior distillates. `According to the present process,` the al1 kylate previously regarded as the :Iinal product' One element ',prelferably intermediate cut, which constitutes something like of the alkylate and has an octane rating of about '70, is taken through line I9 for further processing; while the overhead and bottoms are reunited in pipe to form a hydrocarbon mixture of 97 clear octane number as compared with 94 for the alkylate of line I5.

The intermediate fraction from line I9 is heated in heater 2'I to a temperature proper for dehydrogenating cyclization and passed to a catalyst chamber 22 containing acatalyst for converting aliphatic hydrocarbons to aromatic hydrocarbons. Suitable catalysts, as previously described, are o xides of metals of the IV, V and VI groups of the periodic table, preferably supported una carrier such as alumina or silica gel. Any of the known catalysts for the purpose may be used, temperatures and other conditions of treat-v i ment being adjusted to proper operation with the catalyst selected. For example, chromium sesquioxide on alumina may be used at temperatures of about 500 C. Preferably the conditions of aromatization are maintained relatively mild as c oncerns temperature, pressure and time of contact, since drastic conditions appear to have a substantial detrimental edect.

'l The product of the catalytic treatment in chamber 22 is fractionated in a column to separate a high boiling fraction as the desired composition and an overhead suitable for recycling to the catalyst in chamber 22. The overhead is condensed in a suitable condenser 23 and separated from fixed gases in a separator 24, whence the liquid is returned to line I9 for recycling with a fresh fraction from column I8. The bottoms from column 23 have a blending value in 60-40 octane heptane mixture ofabout 125 A. S. T. M. and may be blended with the mixture in line 20 to produce a blend having a clear(` octane number in excess of 100, usually about 101. Because of the highly aromatic nature of the bottoms from column 23, th'ey are useful for many other purposes in addition to blending with fuel distillates derived from line 20 orpther source. For example, the aromatic mixture is an excellent solvent for resins and the like and may also be utilized as an intermediate in the preparation of explosives and other chemical products of various types. A consideration of the composition of cold sulphuric acid alkylates reveals that the fraction treated according to the present process probably consists predominantly of low octane number dimethyl hexanes.

Some parajins reported in cold acid alkylate (Q5-130 C. fraction) Boiling Percent e Parcdin point N. (approx 2,2,4 trimethyl pentane 99. 23 100 2,5 dimethyl hexane. 109. 25 55. 7 12 2,4 dimethyl hexane. 109. 8 69. 9 2,3,4 trimethyl paritaria... 113.5v 97 2,3,3 trimethyl gentanm 115. l 99. 1 25 2,2,5 trimethyl exmam 124. l 91. 2 4

- I According to the literature relative to aromatization of` pai arlns, m-xylene and p-xylene would result, respectively, from such treatment of 2,4 dimethyl hexane and 2.5 dimethyl hexane respectively, the high octane numbers of these xyf alkylated with butylene in the presence of a fluid lenes would then explain the very marked improvementto be obtained by blending them back to the remainder of the alkylate from which the dimethyl hexanes (it that is their' nature) were removed.

- Reason can also be found here for the above recommendation that 4conditions of aromatization be mild. Drastic conditions would probably result in isomerization of metal and para xylenes to ortho xylene which has a higher boiling pointand lower octane number as shown by the following table: i

Xylen'e isomer' Ortho AMeta Para Blending value in 60-40{A. S. T. M 102. 5 124 126. 6 octane heptane mixture Research 120 134.5 145.5 Boiling point C 144. 05 139.30 138.40

- I claim:

1. A process for preparing a hydrocarbon motor fuel which comprises alkylating iso-butane with butylene, separating from the alkylate product a octanes from which said dimethyl hexanes were separated. 3. In a process for preparing a hydrocarbon fuel of high octane number wherein iso-butane is tion and blending the product of said reaction Y with the remainder of said alkylate fraction.l

4. The process which comprises separating dimethyl hexanes from a mixture of isomeric octanes, subjecting said dimethyl hexanes to a mild dehydrogenatingv cyclization reaction and blending the product of said reaction with the isomeric `octanes from which said dimethyl hexanes were V uct a traction consisting essentially oi' dimethyl hexanes, subjecting said fraction to a mild dehydrogenating cyclization reaction and returning the product of said reaction to said alkylate product. v

6. A composition o1' matter prepared by separating dimethyl hexanes from a mixture of iso- ALFRED w. 

